It is currently common practice, in dry wall construction, to first apply by adhering (as a first step, and by plaster) a tape over each seam, and then after a waiting period of a day or more applying (as a second step) a thin, smooth, layer of finish plaster over the tape. This procedure requires return of the workmen to the job site for the second step, as well as an additional clean-up operation thereafter. As a consequence, dry wall taping is presently time and labor consuming with resultant inconvenience and lack of economy. The present invention was conceived in a successful effort to overcome such problems.